This project identifies a new approach to silicon x-ray detector technology wherein: (i) the detector geometry is changed to provide a much lower capacitance for a given active area and volume, (ii) the conventional Si(Li) detector is replaced with a stable, oxide-passivated, low leakage-current, deep sensitive-depth, v-type Si element, and (iii) the conventional FET in the preamplifier is replaced with an on-wafer FET with improved high frequency noise. The low capacitance and lower preamplifier noise will allow operation at shorter pulse processing times, which in turn will allow higher operating temperatures and improved count rate capability. This approach, which is compatible with hermetic encapsulation, will provide a rugged, environmentally stable Detector/ASIC amplifier package with improved detection efficiency at both high and low x-ray energies, improved count rate capability, and good energy resolution at higher operating temperatures